Field of the Invention
The present invention relates to encoding of images.
Description of the Related Art
In recent years, cameras for monitoring in order for distribution of images via a network are widely used. Some of the cameras perform various types of image processing on an original image according to an intended purpose of use. For example, there is a case where image processing is performed on a main image input as a result of image capture by a camera to generate a sub-image so that, for example, a monitoring target becomes clearly visible, and recognition processing is facilitated.
To transmit both the main image and the sub-image from the camera or to accumulate the main image and the sub-image in the camera, moving image compression is performed. A well-known video coding format used for compression and recording of moving images is H.264/Moving Picture Experts Group-4 (MPEG-4) Advanced Video Coding (AVC) (hereinafter, “H.264”). Further, in recent years, the international standardization efforts were commenced for a more highly-efficient encoding format as a successor to H.264, and a Joint Collaborative Team on Video Coding (JCT-VC) was established by the International Organization for Standardization/International Electrotechnical Commission (ISO/IEC) and the Telecommunication Standardization Sector of the International Telecommunication Union (ITU-T). By JCT-VC, standardization of the High Efficiency Video Coding (hereinafter, “HEVC”) is implemented.
For example, Japanese Patent Application Laid-Open No. 2011-216965 discusses a method in which a plurality of stream images is transmitted using a multiview coding (MVC) standard, which is an extension of H.264. Japanese Patent Application Laid-Open No. 2011-216965 discusses a technique in which a specific video stream among a plurality of video streams is encoded as a base stream and another video stream is encoded using an encoding method by which the video stream can be encoded by reference to the base stream. According to Japanese Patent Application Laid-Open No. 2011-216965, for example, a video stream corresponding to an image captured by a network camera is encoded as a base stream, and a video stream acquired by performing noise reduction on the captured image can be encoded using the encoding method in which the video stream can be encoded by reference to the base stream.
A defog/dehaze technique (U.S. Pat. No. 8,340,461) is well known as image processing for generating a sub-image (video stream encoded using the encoding method in which the video stream can be encoded by reference to the base stream).
However, there is a possibility that the amount of processing is increased in a case of encoding a plurality of images.
The amount of processing is likely to increase especially in a case of generating a sub-image (noise-reduced image) from a main image (captured image) and encoding each of the sub-image and the main image using the MVC standard. Specifically, if a plurality of images including the main image and other sub-images is to be referred to in order to adopt a reference image for encoding the sub-image with high encoding efficiency, the amount of processing is likely to increase because it is necessary to refer to a large amount of images.